The present invention relates generally to window shades for automobile windows, and more particularly, to extendable and retractable automobile window shades.
It is known to employ window shades for protecting the interior of motor vehicles against strong solar radiation. The type of window shades most used so far are the so-called rear window shades. Such a rear window shade is described in EP 87 103 302.3.
The known rear window shade has a base, in which a windup roller is rotatably seated. The windup roller is elastically prestressed in the winding direction of a window shade web with the aid of a spring drive.
One transverse edge of the window shade web is fastened on the windup roller, and its other transverse edge is connected with a pull rod. Next to the windup roller, two pivot levers, which are pivotable around shafts which extend at right angles to the windup roller, act on the pull rod. The pivot levers have flexural strength in a vertical direction in respect to the plane defined by the extended window shade web and in the extended state have the function of keeping the pull rod pressed against the window, or of unrolling the window shade web from the windup roller against the force of the spring drive.
The window shade web of the known rear window shade has a trapezoidal shape, which approaches the complicated shape of the rear window. It is intended by means of this to provide as satisfactory a shading as possible, in that only small areas of the rear window remain unshaded by the window shade.
However, because of its structure, the extended window shade web always forms a plane which extends in the form of chord in front of the usually greatly curved rear window. Since the rear windows of sedans can curve considerably with respect to several axes, the extended rear window shade extends relatively far into the passenger compartment.
It is furthermore known to turn the pivot levers supporting the pull rod around their longitudinal axis at the end of the pivot movement when the window shade web is extended. The pull rod is slightly curved in a parabolic shape by this, so that the window shade web is curved in the same way at the immediate connection with the pull rod. But the windup roller remains straight, so that, starting with the curved shape in the vicinity of the pull rod, the window shade web makes a transition into a level or straight shape at the outlet slit.
Finally, it is known from the prior art to guide the front edge of rear window shades by means of a pull rod, whose ends run in two guide rails. In the latter case, too, the extended window shade web forms a plane, whose edges only approximately follow the curved contour of the window.
Another disadvantage of this solution furthermore lies in that the guide rails and the other drive mechanisms for the window shade must be separately installed in the vehicle.
In this case the conditions are particularly disadvantageous if the window shade web is housed in the vehicle roof. The rear window has the narrowest width at the top edge. The shape needs to be matched to this width, so that with the shade extended, large triangular areas, which are not covered, remain in the lower area.
In view of the foregoing, it is the object of the invention to provide a window shade in particular for motor vehicles, which offers improved user comfort and/or installation ease.
An improved user comfort and a better design can be achieved, if the window can be shaded exactly up to the edges when the window shade is extended. To achieve this, a window shade material which can be changed in width is used in accordance with the invention. The width extension here is the direction which lies transversely in respect to the movement direction when the window shade means are retracted or extended. Because of the width adjustment it becomes possible to practically completely fill the window opening, even in the case where the lateral edges of the window do not extend parallel, but are curved or divergent, or if the window shade web is stowed in an area which only permits a short outlet slit.
By xe2x80x9cchangeable in widthxe2x80x9d, a window shade material is understood here to be designed in such a way that two arbitrary points on the longitudinal edge which are located at the same height experience a relative distance change during retraction and extension.
The window shade material of the window shade in accordance with the invention can be made from a material which is only changeable in width, while it is practically non-expandable in a longitudinal direction, i.e. parallel with the movement path.
Foils which have the desired elastic properties may be used for the window web material, for example foils made from an elastomer. Here it is possible in case the material blocks too much light to improve the entry of light by perforating the foil.
Another possibility of producing the window shade web lies in the use of mesh material, i.e. knit fabrics. As known in connection with clothing, such materials can be expanded in the longitudinal, as well as in the transverse direction. If expandability in the longitudinal direction is undesired, the knit fabric can additionally be provided with non-expandable threads in the longitudinal direction.
The restoring force in transverse expansion is improved if the mesh material is knit from non-expandable threads and elastically expandable threads, for example Elastan(trademark). The material can be produced in the form of plated material. The Elastan(trademark) thread lies only on one side and is not directly exposed to UV light.
A satisfactory adaptation to the respective shape of the window can also be achieved if the window shade material is composed of at least two window shade webs. Moreover, the use of two or more window shade webs has the advantage that the curved, or bowed, shape of the respective window can take an approximated polygon-like shape by means of flat sections which are defined by the extended window shade webs.
By means of this it becomes possible to move the windup rollers for the window shade webs close to the respective edge, for example the bottom edge of the rear window. In this way the rear window shelf behind the rear seat back retains a large surface suitable for placing objects.
When using two or more window shade webs, it is possible to achieve the adjustment in width also without the individual window shade web per se being adjustable in width.
If only one window shade web is used, which is transversely expandable, means are required for pulling the window shade web appropriately wide in the extended state. This can be achieved in the simplest way with the aid of guide rails which extend in a correspondingly contoured way. Expanding means, which run in grooves of the guide rails and pull the window shade web correspondingly wide, are provided for the edges of the window shade material.
The expanding means can be cords, which are present along the entire edge of the window shade web and are provided with a projecting lip. The lip can be hooked behind the undercut edge of a correspondingly shaped groove in order to achieve the desired transverse expansion.
In the course of retracting the window shade web the cord is also wound on the windup roller, for which it appropriately moves out of the guide rollers. In the completely retracted state of the window shade it is sufficient if a short section of the window shade remains guided in the guide rails. In the course of being pulled out, or unwound, the section of the cord seated in the guide rails automatically pulls the still free following section into the guide rails behind itself.
The guide rails can be selectively provided with a single groove for the expanding means and the pull rod, or with two separate grooves, wherein one is provided only for the cord and the other only for the pull rod.
The actuation of the pull rod can take place in any arbitrary manner, such as known from the prior art or from practical experience, for example with the aid of SU flex shafts(trademark), cable pulls, or the like.
In place of guide rails with grooves, rod-shaped guide rails, on which rings slide, which are connected with the edges of the window shade material, can also be used. In this case the stowage device becomes a simple pocket, in which the window shade material is placed in an accordion shape or a fan shape.
Another possibility for stowing the window shade material consists in the use of a windup roller system composed of one or several windup rollers.
If the window shade material is intended to merely extend in a chord-like manner in front of the rear window, a single continuous windup roller is sufficient.
If a curved shape of the window shade material is also desired in the area of the outlet slit, it is practical to compose the windup roller device from two or more individual windup rollers, which are possibly operationally connected with each other. In this case the axes of the windup rollers form angles with each other which are other than 180xc2x0, so that the course of the respective window edge can be approximated in the manner of a polygon.
Even when using a single expandable window shade which can be changed in width, there is the possibility of winding the window shade on one or several windup rollers whose angles to each other differ. In this case the individual windup rollers are operationally coupled with each other so that they run synchronously.
When using two or more non-expandable window shade webs, the gap between the individual window shade webs in the extended state can be minimized, if windup rollers which adjoin each other, or are neighbors, have a reversed winding direction. Because of this the window shade webs can directly adjoin each other and no distance corresponding to the diameter of the windup roller is required between them if overlapping is to be achieved.
Actuation becomes particularly simple if a single common pull rod is used for all window shade webs.
The window shade in accordance with the invention can be advantageously pre-assembled in an assembly frame containing the guide rollers and the stowage device, as well as the drive mechanism. Because of this, the entire unit can be mounted as a complete component in the course of the vehicle assembly.
In accordance with a further aspect of the invention, increased user comfort can also be achieved if the window shade has a window shade material which is composed of at least two essentially non-expandable window shade webs, wherein two arbitrary points on the two window shade webs which are located at the same height do not experience a relative distance change during retraction and extension. It is easily possible by means of such a window shade to approximate the bowed shape of the rear window and to bring the window shade webs as close as possible toward the window, regardless of the extent of the curvature of the window.
The window shade webs can be made of a foil which is impervious to light and whose transparency can be fixed in the desired way by perforations.
In this embodiment, two variations can be used as guide means. One variation consists in the use of the known guide rails, in which the ends of the pull rod are guided and on which the transverse edges of at least two window shade webs have been fastened. Since with this embodiment the longitudinal edges of the window shade material are not acted upon by transverse forces, they need not be guided or held in the guide rails. Under these circumstances a solution by means of levers can also be used for extending the window shade web. This provides at least two pivotable toggle levers, which have flexural strength and are pivotally seated at the windup roller and whose other ends are connected slidingly, in the case of the pivot lever, or hingedly, in the case of the toggle lever. Here, too, a pull rod is preferably employed which is common to all window shade webs and whose angle essentially matches the angle at which the windup rollers for the window shade web are arranged in respect to each other.
So that, depending on the special embodiment of the window shades, no creases appear in the extended window shade web, the respective transverse edge of the window shade web is preferably displaceable in respect to the pull rod in the direction parallel to the longitudinal extent of the latter.
With this type of window shade, the stowing means can be a simple pocket, in which the window shade webs are folded and stored, or it can comprise a windup roller system on which the window shade webs are wound.
Suitably the windup roller system is composed of several windup rollers, which are moved synchronously in respect to each other and which are arranged at a defined angle in respect to each other, in order to achieve the polygon-like approximation to the window curvature.
The gap between the window shade webs can be made particularly narrow if the window shade webs overlap each other, to which end the windup rollers are suitably wound in opposite directions. Because of this, the window shade webs can adjoin each other directly without having to maintain a gap between them which corresponds to the wound-up roll on the windup roller.
A particularly good approximation to a strongly curved rear window surface is achieved by means of three window shade webs.
The window shade in accordance with the invention with at least two non-expandable window shade webs can be advantageously pre-assembled in an assembly frame containing the guide rollers and the stowage device, as well as the drive mechanism. Because of this, the entire unit can be mounted as a complete component in the course of the vehicle assembly.
Instead of winding the window shade web directly on the windup roller, there is also the option of attaching pulling means to the rear edge of the window shade web, which are wound on disks, which are appropriately spaced apart from each other. Or, the rear transverse edge is also provided with a pull rod on which a drive mechanism acts.
Finally, a very easy mounting can be achieved if the window shade is pre-fabricated as a mounting unit independently of the type of the window shade material. This mounting unit contains the guide rails, as well as the drive mechanism and the windup rollers and the like. The mounting frame is furthermore provided with fastening means for attachment to the vehicle.
Otherwise, the window shade can be embodied as described above in respect to the windup rollers and further design of the window shade web to the extent that this is technically useful.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: